The present invention relates generally to generating X-rays, and specifically to an improved method and system for generating X-rays using a field emitter X-ray source.
X-ray systems are generally utilized in various applications, such as for imaging in the medical and non-medical fields. For example, X-ray systems, such as radiographic systems, computed tomography (CT) systems, and tomosynthesis systems, are used to create images or views of tissues of a patient based on the attenuation of X-ray beams passing through the patient. X-ray systems and sources may also be utilized to in non-medical applications, such as detecting minute flaws in equipment or structures, and scanning baggage, crystallography, to mention only a few.
Typically, a X-ray system includes an X-ray source that generates X-ray beams that are directed towards a detector or film. Conventional X-ray tubes generate a beam of X-rays by bombarding a rotating anode with a stream of electrons in vacuum tube. More recent developments have provided a design in which an electron source, such as an array of field emitters, and an anode assembly, are housed inside an evacuated tube. The field emitters include sharp tips that are subjected to high electric currents to emit electrons by a phenomenon called field emission. The electrons thus emitted, travel across an open space at very high speeds and collide with the anode assembly to produce the X-ray beams.
In field emitter X-ray sources, the tips of the field emitters can become degraded by deposition of oxides and other contaminations. A low level of contamination in field emitters may be tolerated in applications such as flat panel displays. However, these contaminations can significantly affect the performance of the field emitters that are subjected to very high electric currents in applications such as X-ray systems.
Thus, there exists a need for an improved field emitter X-ray source for generating X-rays. There is a particular need in the art for techniques that will limit or correct the deposition of contaminates in field emitter arrays, thereby permitting the arrays to be more effective over a longer useful life.